Turbine disk



Feb. 10; 1953 A. A. LOMBARD ETAL 3 Sheets-Sheet l K S I D E N I B R U T Feb. 10,1953 A. A. LOMBARD ETAL TURBINE DISK 3 Sheets-Sheet 15 Filed Oct. 2, 1947 Patented Feb. 10, 1953 TURBINE DISK Adrian Albert Lombard and Frederick William Walton Morley, Clitheroe, Christopher Ainsworth Davis, Barnoldswick, and Stanley Clarke Wilkinson, Colne, England, assignors to Rolls- Royce Limited, Derby, E

Pa y

ngland, a British com- Application October 2, 1947, Serial No. 777,506

In Great Britain October 2, 1946 This invention relates to gas-turbine and more particularly to turbine-disc-assemblies of the kind in which the turbine-disc comprises two complementary parts spaced axially and supporting peripherally the turbine-blading therebetween. In such constructions it has been proposed to provide a space between two parts of the disc forming a passage for air cooling the discand blades and/ or their fixing.

In gas-turbine engines for aircraft-propulsion, to which the invention is particularly though not exclusively applicable, it has been the practice to manufacture turbine-discs from solid forgings, which in order to accommodate for high centrifugal loading and to avoid vibration or fwhip, have been of relatively thick section. In addition, owing to the elevated temperature at the periphery of the disc it has'been necessary to manufacture a disc from special high temperaturesteels. by applying air on'one face and deflecting the air at the outer periphery of the disc to cool the blade root fixings; in practice, however, such cooling has been relatively ineffective.

The object of the present invention is to provide'a turbine-disc and blade-construction which will facilitate manufacture, provide a lighter construction than hitherto and improve the blade or blade-root cooling efiiciency.

The nature of the invention will be appreciated by reference to the following description of preferred embodiments illustrated in the accompanying drawings, in which:

Figure 1 is a local radial section through a turbine disc,

Figure 2 is a partial end view of Figure l with parts broken away, and

Figures 3 and 4 illustrate an alternative construction of blade mounting.

Referring now to Figures 1 and 2, which illustrate a preferred construction in which each blade is formed-with a root to be engaged directly with the halves of the turbine-disc, the turbine-disc comprises two generally similar dished disc parts 40, 4| assembled with their concave faces together. The disc part4!) is formed externally with a flange 42 by which the turbine disc is secured to a hollow shaft 43, and each of the disc parts 40, 4| is centrally bored and has an internal, radially-inwardly directed flange M inthe bore by which they are bolted together at their centre. A closure plate 45 is secured to-the flange 44 on. disc part 4| and the flanges 44 are formed with registering slots 45 by which-cooling air delivered into' the central bore through the Such turbine-discs have been cooled 6 Claims. (Cl. ass-39.15)

2 shaft 43 is conveyed into the'interior of the turblne disc. A sleeve 41 is spigotted on internal shoulders Moon the disc parts to assist in restraining the disc parts against relative radial movements, and the sleeve 41 is slotted at $8 to register with the outer ends of slots 46. A pair of diametrically-positioned locating-studs llf are provided on the sleeve 46 to e'ngage'in recesses 50in the shoulders 44a.

' rivets are located on a circle the radius of which is greater than 1 the radius of the annular shoulders 51 so that the rivets arev positioned at a pointin the turbine disc which is subject to considerably, reduced centrifugal stresses. The

' blade roots 153 are cut away, as'lwill be seen from Figure 2' to'per'mit the passage of'the rivets securing the discstogether and the thickened portion of the disc peripheries are formed with axially projecting lands 55 which extend between the blade roots and abut one another. The function of the upstanding lands is to determine the spacing of the disc parts attheir periphery and to ensure a slight clearance between the inside surface of the thickened periphery andthe blade roots to permit the flow of coolingair outwardly between the disc peripheries and the blade roots to cool them. Recesses 51 are formed in the adjacent ends of the blade roots to form channels for the passage of cooling air outwardly to between the thickened peripheral portions of the discparts 40,1. i

The-.disc'parts 40, iii are also provided at a distance from their centres equalto approximately half their maximum radius with internal axially directed flanges 69 to formsockets to receive a ring 5! which engages in the sockets-spigotwise and determines the spacing ofthe disc-parts at this point. Radial air transfer slots 62' are cut in each side face ofthe ring Bi and transverse channels-63 are formedon theouter face ofthe ring by. features 64 upstanding between the fiangestm the channels 63 connecting the outer ends of the slots 52 and ensuring mixing of the air streamsv from the slots to preventstratification;

The upstanding features 64 are connected to one another between the channels 63 by a narrow strengthening web 65.

A further internal axial flange 66 is provided between the flanges 60 and the thickened periphery to constitute sockets to receive a second spacer ring 61 spigotwise. Air transfer slots 68 are formed in the side faces and outer face of this ring.

The spigot-like couplings between the ring Bi and the disc parts 40, 4|, and between the. ring 67 and the disc parts and also the coupling provided by the sleeve 41 and shoulders 44c. serve to resist the centrifugal gyroscopic. or thermal loading tending to cause the discs to move relatively to one another in a radial direction.

The disc parts 49, 6| will conveniently be made from a material such asthat known bythe. trademark Hykro and the blades with their integral roots from the material known as Nimonic which is capable of withstanding the high temperatures under which it will operate. The rings 6!, ill will conveniently be formed from material such as aluminium having a high coeiiicient of expansion. so that they will tend to tighten in their sockets as the temperature rises.

In the alternative form of blade root fixing illustrated in Figures 3 and 4, the turbine disc is of; similar construction to that illustrated inFigures l and 2, and like reference numerals are used in these figures to indicate like parts. The disc parts til and 41 are formed as in the. previous onstructi n with, thickene periph r s t pr vide shoulders. 5|- to engage. complementary shouler or spi o elem nts 5.4 on. the blade roots. 53 of the turb ne. blades 5.2 The. thickened peripheries are. also provided with, axially-projecting lands 55 o determine. the spacing of the discs which are secured together by counter-sunk bolts 56 engaging in nuts in. The spacing of the disc parts mayv provide axial clearance. in the blade-root fixing for the passage and metering of cooling air.

The disc. parts 4.0, M in this construction are formed; additionallywith annular channels H to provide a, second shoulder for engaging arcuate projections." onthe blade. roots. so that the loading of 'the disc parts due to the centrifugal stresses generated by the blades. is distributed over a.

greater. portion of the disc periphery. The disc. securing bolts 56. are positioned ona. circle which lies in a portion of the periphery substantially outside the area subjected to these stresses.

It will be appreciated that the constructions of turbine discabove described are relatively light in weight and yet are capable of withstanding the high stresses experienced when in use, are rela-- tively simple tomanufacture, and by virtue of the method of blade-root f xing have an improved cooling efliciencyas regards the blade-root cooling. Cooling air may also be passed over the outer surfaces of the turbine disc.

For example, as shown in Figures land 2, cooling air may be suppliedto the outer faces of the disc-partsasindicated by thearrows. The discpart 40 may be considered to be on the high pressure sideofthe, turbine whilst the disc-part 4| is on the low pressure side thereof. The cooling air supplied-to the face of thedisc do is thus at high pressure, whilst that supplied to the face of the disc 41 can beatlow pressure. The cooling air supplied is preferably metered in such a manher as to providesubstantial uniformity of temperature distribution overthe two discs and thus avoid; as far as possible, thermal'loading tending to displace the disc parts radially relative to one another. In such an assembly it is preferred to provide a degree of axial nip between the two parts, which will accommodate for the differential pressure existing between the interior of the disc (at relatively high pressure) and the downstream side of the disc part ll (at relatively low pressure) Moreover by locating the screws, bolts or rivets for securing the discs together outside the region of the part of their peripheries subjected tohigh centrifugal stresses, the discs are not unduly weakened by the provision of the holes to receive the bolts, screws. or rivets.

Furthermore, the, construction of turbine disc or this invention enables the various parts of the disc to be manufactured from a material having the desired strength properties at the temperature at which it will operate. Thus the dished discs may be formed from a material having desired strength properties at a temperature which is moderate as compared with that at which the blading or the blade-supporting ring will operate and the blading or blade-supporting ring will be made from a material having desired strength properties at a more elevated temperature.

What we claim is:.

1. An axial flow turbine assembly comprising in combination two complementary disc parts secured to each other and axially spaced to provide a hollow space therebetween; meansf or'supplying cooling gas to said space; peripheral shoulder means on said disc parts extending axially towards one another; a plurality of axial flow turbine blades arranged in circumferential assembly and having blade root portions; and an axially extending circumferential spigot element on each of; said blade root portions to engage in radial outward abutment with said axially extending peripheral shoulder means on said disc parts; securing members extending through the disc parts and. between adjacent blade root portions and located at a radius outside said spigot elements; spacer means located between adjacent blade root portions to space the disc parts axially independently of said blade root; portions; and passages provided between said peripheral shoulder means. and said blade. root portions and communicating between saidspanc.

and the exterior of the assembly to permit, the flow of cooling gas from said space.

2'. An axial flow turbine assembly, comprising in combination two complementary disc parts secured together and axially spaced to provide a hollow space therebetween; means for supplying COOlll'lg gas to said space; peripheral shoulder means on said disc parts extending axially towards one another; a plurality of axialfiowtillbine blades arranged in circumferential assembly and having blade root portions; an axially extending circumferential spigot element 0.11- each of said blade root portions toeh a in radial outward abutment of the elgmentwith Said axially extending peripheral shoulder means; on said disc.

parts; securing, members extending through the.

disc parts and between adjacent. turbine blade root portions and located at a radius outside said spigot element; spacer means located be tween adjacent blade root portions to space the disc parts axially at a radius outside said spigot:

- which passages communicate between saijdspace and the exterior of the assembly to permit the flow of cooling gas from said space, such flow cooling the blade root portions and peripheral portions of the discs by direct contact therewith. 3. An axial flow turbine assembly, comprising in combination two complementary disc parts secured together and axially'spaced so as to provide a hollow space therebetween; means for supplying cooling gas to said space; peripheral shoulder means on said disc parts extending axially towards one another; a plurality of axial flow turbine blades arranged in circumferential assembly, and having blade root portions; axially extending circumferential spigot elements on each of said blade root portions to engage in radial outward abutment with said axially extending peripheral shoulder means on said disc parts; securing members extending through the disc parts and between adjacent turbine blade root portions and located at a radius outside said spigot elements; axially directed lands circumferentially disposed on said discs to extend between adjacent turbine blade root portions and to interabut to space the disc parts axially at a radius outside said spigot elements independently of said turbine blade root portions, and interconnecting passages constituted between adjacent turbine blade root portions and between said blade root portions and disc parts by virtue of said independent spacing, which passages communicate between said space and the exterior of the assembly to permit the flow of cooling gas from said space, such flow cooling the blade root portions and peripheral portions of the discs by direct contact therewith.

4. An axialflow turbine assembly comprising in combination a turbine rotor shaft; two complementary disc parts supported by said rotor shaft and axially spaced to provide a hollow space therebetween; means for supplying cooling gas to said space; peripheral shoulder means on said disc parts extending axially towards one another; a plurality of axial flow turbine blades arranged in circumferential assembly and having blade root portions; axially extending circumferential spigot elements one on each of said blade root portions to engage in radial outward abutment of said spigot elements with said axially extending peripheral shoulder means on said disc parts; se-

curing members extending through the disc parts and between adjacent blade root portions and located at a radius outside said spigot elements; means for spacing the disc parts axially at a radius adjacent said securing means independently of said turbine blade root portions; axial abutment means on said disc parts defining said axial spacing at an inner radius adjacent the radius of the shaft; circumferential shoulder means on said disc parts extending axially into said space and located at a radius between said peripheral shoulder means and said abutment means; a spacer ring in said space engaged in axial abutment by said disc part and to engage in radial outward abutment with said circumferential shoulders; passages formed in said ring to permit the passage of cooling gas radially outward through said ring; and interconnecting passages constituted between adjacent blade root portions and between said blade root portion and disc parts by virtue of said independent spacing, which passages communicate between said space and the exterior of the assembly to permit the flow of cooling gas from said space, such flow cooling the blade root portions and peripheral portions of the discs by direct contact therewith.

5.-An axial flow turbine assembly comprising in combination two complementary disc parts secured together and axially spaced to provide a hollow space therebetween; means for supplying cooling gas to said space; first peripheral shoulder means on said disc parts extending axially towards one another; second peripheral shoulder means on said disc parts extending axially towards one another and located at a radius outside said, first peripheral shoulder means; a plurality of axial flow turbine blades arranged in circumferential assembly and each having blade root portions; a first axially extending circumferential spigot element on each of said blade root portions to engage in radial outward abutment of the element with said first peripheral shoulder means; a second circumferential spigot element on each of said blade root portions to engage in radial outward abutment of the element with said second peripheral shoulder means; securing members extending through the disc parts and between adjacent turbine blade root portions and located at a radius between the first and second peripheral shoulder means; spacer means located between adjacent blade root portion to space the disc parts axially at a radius outside said first spigot elements independently of said turbine blade root portions; and interconnecting passages constituted between adjacent turbine blade root portions and between said blade root portions and said disc parts by virtue of said independent spacing which passages communicate between said space and the exterior of the assembly to permit the fiow of cooling gas from said space, such flow cooling the blade root portions and peripheral portions of the discs by direct contact therewith.

6. An axial flow turbine assembly comprising in combination a turbine rotor shaft; two complementary disc parts supported by said rotor shaft and axially spaced to provide a hollow space therebetween; means for supplying cooling gas to said space; peripheral shoulder means on said disc parts extending axially towards one another; a plurality of axial flow turbine blades arranged in circumferential assembly and having blade root portions; axially extending circumferential spigot elements one on each of said blade root portions to engage in radial outward abutment of said spigot elements with said axially extending peripheral shoulder means on said disc parts; securing members extending through the disc parts and between adjacent blade root portions and located at a radius outside said spigot elements; spacer means located between adjacent blade root portions to space the disc parts axially at a radius outside said spigot elements independently ofsaid turbine blade root portions; axial abutment means on said disc parts defining said axial spacing at an inner radius adjacent the radius of the shaft; circumferential shoulder means on said disc part extending axially into said space and located at a radius between said peripheral shoulder mean and said abutment means; a spacer ring in said space engaged in axial abutment by said disc parts to engage in radial outward abutment with said circumferential shoulders; passages formed in said ring to permit the passage of cooling gas radially outward through said ring and interconnecting passages constituted between adjacent blade root portions and between said blade root portions and disc parts by virtue of said independent spacing which passages communicate between the said space and exterior of the assembly to permit the flow of cooling gas from said space, :such flow cooling the blade root portions and peripheral port-ions of the discs by direct-contact therewith. i ggg ADRIAN ALBERT ILOMBARD. 2141401 FREDERICK WILLIAM WALTON MORLEY. 2401826 CI-BISTOPHERADJSWORTHDAVlS. STANLEY CLARKE WILKINSON.

Number REFERENCES CITED 319 622 The :following references are n! record in the 1 340. 93 file of this patent: 345,984

8 UNITED STATES PATENTS Name Date Robinson May 15, 1934 Martinka Dec. 27, 1938 Halford June 11, 1946 FOREIGN PATENTS Country Date Great Britain :Dec. 18, .1930 Germany July 1,, 1920 France vNov. 8, I904 

